Staffers in the office of a Deputy Commissioner of Police in Delhi are under a cloud of suspicion following the disappearance of a highly sensitive book, which contains intricate details about the security details of VVIPs and vital installations.

Several police personnel have been questioned in connection with the about two-year-old incident but there has been no progress, police sources said on Saturday.

The disappearance of the book from the office of DCP (East District) was detected in October 2002 but a case was registered only recently after efforts to recover the sensitive document yielded no results.

Police suspect some of the staffers in the DCP's office may have been involved in the disappearance of the vital document but nobody has been arrested so far.

The book is distributed only among top police officials and it contains details of security drills.